On 6/16/2016 7:40 PM, Steve Cottrell wrote:
On 16/6/16, P.J. Alling, discombobulated, unleashed:
Then they missed the mark. Video shooters want not just silent
operation, but step-less aperture adjustments as well. The current
camera bodies don't support this and I don't see how they can, the
control wheels are obviously digital jog switches. To get step less
control would probably require an analog wheel control.
Yup. It's called an aperture ring.
Look at all the 'cine' versions of lenses produced. Manual focus and
manual aperture.
The Canon EF17-40/4 I use on a Canon C100 is fine except for the
camera-
controlled aperture, which even when set to finest adjustment, still
produces notable steps in light - unacceptable in video. So I bought
the
only comparable wide zoom with a physical aperture ring on ot, the
Nikkor 16-35/2.8 and had it converted - the aperture ring 'de-clicked'
and dampened, and an EF mount installed. Works great and cost a lot
less
than a dedicated wide zoom cine lens.
Incidentally the A*85/1.4 in similar guise works superbly for video.
This is what I've been trying to imply. But no one is taking the hint.
First off how does the jog wheel work? Each time you move it a click,
it changes a setting by a programed increment. It's a digital device it
reads clicks either plus or minus. In photo-terms either one stop, half
stop, third stop. Those are unacceptable in film making. So lets make
it finer, what will the user put up with? Assume we can divide the
aperture range into some easy to implement graduation that can emulate
an analog device like a de-clicked aperture ring. Say a range that
programmers like, say 0-255, that's a pretty fine gradient. Each click
opens or closes the aperture by 1/255 of it's range from for example
f2.8-f22.
The user is going to be turning that wheel a lot, and getting mighty
pissed doing it. So let's anticipate turning it fast if the user wants
bigger increments, (it's been done just like zoom by wire, and focus by
wire systems), film makers hate them. Turn too fast you over shoot, or
get noticeable changes in aperture, (like having fixed click stops), in
the footage.
Then I've noticed on every weather sealed Pentax camera I own, sometimes
when you move the wheels too fast the camera loses a click or two or
three or more, I turn the wheel on either the K-5II, or K20D quickly for
a several stop fast change and the camera changes exposure a third of a
stop, I put up with it turn the wheel a little slower and it works
fine. It's not going to help get that smooth transition in exposure in
"film" footage.
No, aperture by wire is not a change that Cinematographers want.
Programming the wheel to even try to anticipate what they want, will be
a nightmare, and be sure to piss somebody off, probably piss everybody
off to some extent.
But this is all moot, I have no idea, and neither does anyone else here,
have any idea, how the aperture is implemented mechanically in the new
lens, for all I know it's a stepper motor and which is it's physical
limitation of how fine the aperture changes can be.
